<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>js函数</title>
		<script>
		   function add(a,b="ok"){
			   return a+b+c;
		   }
		   var c=add(10,3);
		   alert(c);
		   var c2=add("good"," idea");
		   alert("?"+c2);
		   var c3=add("good");
		   alert(c3);
		</script>
	</head>
	<body>
	</body>
</html>
